2-4
Chapter 2
System Boards
y
G.165 compliance, 16ms echo canceler
y
DTMF detection and generation function
y
U-Law/A-Law support
y
Input/Output Gain Control
y
VAD/CNG support
SLC Part
The SLC (Subscriber Line Circuit) part provides four analog telephone ports and allows
connection to a Private Branch Exchange (PBX), the loop start trunk port of a Key Telephone
System (KTS) or a connection to a general analog telephone through each port.
The features and functions of the SLC part are as follows.
y
It provides a current of -48VDC for the connected subscriber telephone.
y
It provides the Ring signal that indicates the subscriber telephone is ringing.
y
It reads the hook ON/OFF status, dial pulse, Ring trip, call answer status of the subscriber
telephone.
y
It protects the subscriber circuit and system from lightening or high voltages, AC voltage
crossing etc. that are generated from the subscriber line.
y
It converts the analog signal into a digital signal with the PCM method to send them to the
control module. It also converts the digital signal with the PCM method into an analog
signal.
y
It provides hybrid function to separate the sending path and receiving path from the analog
voice signal.
